There is a growing need, in the field of wireless communication, to accurately and securely determine distances (ranging) between wireless devices (e.g., wireless stations (STAs) and access points (APs)). Existing approaches to determining distances between wireless devices are vulnerable to physical-level security attacks from malicious actors, such as denial of services attacks, perturbation attacks, and spoofing attacks.
Spoofing attacks are potentially the most dangerous form of security threat when performing ranging between wireless devices. During a spoofing attack, the attacker interferes with the victim's ranging and is able to control (“spoof”) the victim's perceived range. For example, some applications for wireless ranging require heightened security, such as when using wireless ranging for accessing electronic door locks, computer locks, and ATMs that provide access to funds of a bank account. In these cases, the spoofed ranging measurement should be identified as invalid and discarded to prevent property loss.
Other forms of security attacks concerning wireless ranging, such as denial of service attacks, are very difficult to protect from. In a denial of service attack, the attacker interferes with the ranging signal in such a way to prevent the AP from providing services as intended. Perturbation attacks interfere with the victims ranging, but the attacker is unable to control the resulting range as perceived by the victim.
Existing work has indicated that for security purposes, in high efficiency (HE) and very high throughput (VHT) modes, the fields over which range measurements are performed, such as long training fields (LTF), should be protected against a VHT/HE Type B adversary attack. Further, for the purposes of the physical (PHY) security mode, the field used to channel/time-of-arrival (TOA) measurement should not include any form of repetition in the time domain, or any structure that is predictable.
What is needed is a technique for signaling between wireless devices that enables LTF protection to prevent spoofing attacks in single user (SU) and multi-user (MU) modes.